1. Field of the Invention
This invention relates to a connector for securing together two components.
It relates in particular but not exclusively to a connector of the so-called blind fastener type and which may be employed to clamp together two components in an arrangement in which the surface of one of the components to be acted upon by the clamping force is not accessible for provision of a tool to assist in creating the clamping force.
2. Description of the Related Art
Blind fastener type anchoring devices frequently are employed in situations in which it is desired to attach a component to a member only one side of which is accessible. Examples of such members are a wall surface the reverse side of which is not readily accessible, or a hollow metal section the interior of which is not readily accessible.
It is known to provide a blind fastener type anchoring device which comprises a threaded bolt having a bolt head at one end. A conical expansion head is threadedly mounted at the other end of the bolt. Also surrounding the bolt and abutting against the bolt head is an apertured sleeve head plate. Finally, extending between the sleeve head plate and the conical expansion head is a longitudinally slit, circumferentially expandable, tubular sleeve.
The sleeve head may be integral with the tubular sleeve of the anchoring device or may be independent but arranged to provide a reaction face against which the sleeve may bear, either directly or via an interposed member, when the anchoring device is tightened. The sleeve head is selected to have a cross-sectional size which exceeds that of the sleeve such that an abutment face region of the sleeve head lying outwards of the sleeve may bear against a support member relative to which the anchoring device is being secured.
Prior to insertion in an aperture the expansion head is threaded along the bolt until it abuts against the sleeve. The engagement between the sleeve and the expansion head then restrains the expansion head from turning when the bolt is rotated within the sleeve.
In order to fasten a component to a support member an aperture in the component is first aligned with a corresponding aperture in the support member. The bolt and the sleeve of the fastening device are then inserted through the aligned apertures until the sleeve head plate abuts against the component. The bolt is then tightened. Because the engagement between the conical expansion head and the sleeve prevents the conical head from rotating with the bolt, the tightening of the bolt causes the conical head to be drawn along the bolt towards the bolt head. This forces the longitudinally slit sleeve to expand radially outwards. Eventually the sleeve expands into contact with that material of the support member which defines the aperture in the support member. In consequence the component and the support member become gripped between the sleeve plate and the expanded distal end of the sleeve.
For the purpose of constructing the assembly, a gripping tool is attached to the sleeve head to prevent rotation of the sleeve head plate, and a tightening tool is attached to the bolt head and rotated relative to the sleeve, thereby to tighten the fastening device. A tool as described in our UK patent GB 2410713B may be employed.
Although blind fastener devices of the aforedescribed type generally may function satisfactorily, particularly for low loading applications, they suffer certain disadvantages. In the case of a sleeve and sleeve head being formed integrally with one another it is found that the fastener commonly is not able to achieve the degree of clamping force necessary. In particular it is not possible reliably to achieve the clamping force necessary to comply with the requirements of certain safety standards such as, for example, that of an ICC standard. A further disadvantage is that in order to provide for the axial compression which is taught as being necessary by GB 2421554 and GB 2311579 the sleeve needs to be machined to form a circumferentially extending groove, thus adding to the manufacturing cost.
In the case of a fastener of the type having a sleeve which is not integral with a sleeve head plate it is known to provide therebetween an axially compressible washer which is intended, in use, to resist relative rotation of the sleeve and sleeve head plate and to provide the fastener with the required axial compressibility feature. However it is found that the washer cannot be relied on to resist said relative rotation. Therefore there is the risk that the fastener is mistakenly assumed to have been properly fitted and tightened. A further disadvantage of this type of fastener is that it requires provision of five components, which adds to the manufacturing and assembly costs as compared with a fastener comprising fewer components.